This invention relates to an endoscope and light source apparatus wherein the position of the tip part of an endoscope insertable part can be confirmed outside the body by means of a transmitted light.
Recently, there is extensively utilized an endoscope (called also a scope or fiber scope) whereby organs within a body cavity can be observed and various therapeutic treatments can be made by using, as required, treating instruments inserted through treating instrument channels.
There are also suggested various electronic scopes using such solid state imaging device as a charge coupled device (CCD).
Among color image imaging systems of such electronic scopes, there are such frame sequential type wherein an illuminating light is sequentially switched to R (red), G (green) and B (blue) as is shown, for example, in the publication of Japanese patent application laid open No. 82731/1986 and such color mosaic type (called also a simultaneous type) wherein a filter array in which color transmitting filters transmitting respectively such color lights as of R, G and B are arranged in the form of a mosaic is provided on the front surface of a solid state imaging device as is shown, for example, in the publication of Japanese patent application laid open No. 76888/1985.
On the other hand, in observing the interior of a body cavity with an endoscope, there is known a technique of confirming the position of the endoscope tip part with an illuminating light emitted from the tip part of the endoscope and transmitted outside the body. However, in confirming the position with such transmitted light, in the above mentioned frame sequential type electronic scope, as the illuminating light is separated into respective color lights by a color separating filter, the illuminating light amount will be reduced to be so low than in the color mosaic type radiating a white color light to the object that it will be hard to confirm the tip position. In order to solve this problem, there is disclosed as shown, for example, in the publication of Japanese patent application laid open No. 2927/1987 a technique of removing the color separating filter from the light path to increase the light amount even when the frame sequential type electronic scope is being used.
However, in case the rotary filter is retreated or merely the light amount is increased as mentioned above, in the electronic endoscope or fiber scope, such a large amount of illuminating light will be radiated to the part to be observed that the observed part has been likely to be burned by the heat of the illuminating light.